The invention relates generally to ultrasonic imaging methods for industrial applications and, more particularly, to improved ultrasonic imaging methods for the detection of defects found in components and structures (collectively termed xe2x80x9ccomponentsxe2x80x9d) found in industrial settings using advanced phased array ultrasound systems.
Both the use of lighter components in industrial applications and the use of industrial components over longer engineering design lives have increased the demand for enhanced nondestructive inspection techniques designed for industrial settings. To meet current demands, it is necessary to detect smaller defects with greater productivity. Medical imaging tools, such as the GE LOGIQ 9 and the GE LOGIQ Book, include many features that would be desirable for industrial applications.
Conventional ultrasonic inspection systems for industrial applications employ either probes with fixed focus lenses or limited capability phased array imaging techniques. Limitations include performing inspections within the focal depth of field, in the case of the fixed focus lens systems, or within the limits of the phased array system to produce a focused beam. Generally, conventional ultrasonic systems for industrial applications use either a single probe, in pulse echo mode, or a pair of probes, in either a through transmission or pitch and catch mode. These probes can be either unfocused or focused using an attached lens. Industrial inspections requiring high sensitivity over a large depth range are typically accomplished using multiple scans with appropriately focused probes. Such inspections are time consuming due to the multiple scans required. High-sensitivity, large depth range inspections are also performed using a multi-zone approach, in which multi-channel acquisition systems are used to monitor data from multiple probes simultaneously, with each probe monitoring a separate depth within the test component. Conventional ultrasonic inspection systems for industrial applications are typically limited to a single angle beam interrogation of the test component. The angled ultrasonic beam is produced either by affixing the probe to a wedge of material at an angle relative to the test component or by immersion of the probe in a material with a material velocity, which is sufficiently different from that of the test component to cause refraction of the beam.
Conventional phased array imaging ultrasound systems for industrial inspections typically are limited to beam-forming, with the more advanced of these systems providing dynamic depth focus but incapable of performing dynamic aperture sizing. Dynamic aperture sizing is desirable to control the beam properties.
It would therefore be desirable to provide an inspection method for industrial applications that provides both dynamic focus and dynamic aperture sizing. It would further be desirable for the method to compensate for refraction at an interface between a test component and a standoff, for example a water standoff. It would also be desirable to provide an inspection method for industrial applications that compensates for the steering of the ultrasonic transmission beam due to refraction at a test component/standoff interface. In addition, it would be desirable to correct for surface geometry effects caused by a curved test component/standoff interface. To increase productivity, it would also be desirable to provide a single-turn inspection method, so that industrial components can be inspected without time-consuming movement of a probe. It would also be desirable to provide a method to inspect the quality of the product flow through pipes that employs ultrasonic inspection techniques. To decrease inspection time, it would be desirable to employ full-array insonification. Also, for industrial applications, it would be desirable to introduce synchronization of images with the corresponding probe position to advanced ultrasound imaging systems typically employed for medical applications.
Briefly, in accordance with one embodiment of the present invention, a method of inspecting a component is provided. The inspection method includes exciting a number of transducers forming an array to produce an ultrasonic transmission beam focused into the component along a selected ray path from the array. The array is separated from the component by a standoff with a material velocity vw. The inspection method further includes generating a number of echo signals using the transducers as receive elements and processing the echo signals in a number of channels. The processing includes dynamically focusing the echo signals along the selected ray path on at least one focal point P in the component. The dynamic focusing comprises adjusting a delay profile to compensate for refraction of the ultrasonic transmission beam at an interface between the component and the standoff and applying the delay profile to the echo signals in the respective channels to generate a number of delayed echo signals. The processing further includes adjusting the number of active receive elements as a function of a range Rg, to provide a dynamic aperture on receive. The adjustment of the number of receive elements comprises compensating for refraction of the ultrasonic transmission beam at the interface between the component and the standoff. The processing also includes summing the delayed echo signals from the active receive elements to generate a focused echo signal.
Another method embodiment for inspecting a component includes applying a separate excitation pulse to each transducer in the array, to produce an ultrasonic transmission beam focused into the component along a selected ray path. As above, the array is separated from the component by a standoff with a material velocity vw. The inspection method further includes steering the ultrasonic transmission beam along the selected ray path at an angle xcex8 relative to a surface normal. The steering comprises adjusting a transmit delay profile, to compensate for refraction of the ultrasonic transmission beam at the interface between the component and the standoff, and modulating the excitation pulses with the transmit delay profile. The inspection method further includes generating a number of echo signals using the transducers as receive elements and processing the echo signals in a number of channels using a delay profile that comprises a number of receive delays, each receive delay comprising a static receive steering term. The echo signal processing includes adjusting each of the static receive steering terms to compensate for refraction of the ultrasonic transmission beam at the component/standoff interface, applying the delay profile to the echo signals in the respective channels to generate a number of delayed echo signals, and summing the delayed echo signals from the receive elements to generate a steered echo signal.
A single-turn method embodiment for inspecting a component having an inspection surface is also provided. The single-turn inspection method includes (a) positioning an array of transducers facing the inspection surface of the component, (b) exciting the transducers to produce an ultrasonic transmission beam focused into the component along a selected ray path from the array, (c) generating a number of echo signals using the transducers as receive elements, (d) changing the relative angular orientation of the array and the component around an axis and repeating steps (b) and (c), and (e) processing the echo signals in a number of channels to form at least one processed echo signal.
A method embodiment for inspecting product flow through a pipe is also provided. This inspection method includes exciting a number of transducers forming an array to transmit ultrasonic energy into the pipe, generating a number of receive signals from the reflected ultrasonic energy, and processing the receive signals in a number of channels. The processing comprises comparing the receive signals to a frequency reference to determine a number of frequency shifts imparted to the reflected ultrasonic energy.